EP1686443A1 - Verfahren ,Systeme und Computerprogramme zur Durchführung von Zustandsüberwachungen - Google Patents

Verfahren ,Systeme und Computerprogramme zur Durchführung von Zustandsüberwachungen Download PDF

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Publication number
EP1686443A1
EP1686443A1 EP06250485A EP06250485A EP1686443A1 EP 1686443 A1 EP1686443 A1 EP 1686443A1 EP 06250485 A EP06250485 A EP 06250485A EP 06250485 A EP06250485 A EP 06250485A EP 1686443 A1 EP1686443 A1 EP 1686443A1
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EP
European Patent Office
Prior art keywords
event
machine
signature
kernel
display device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP06250485A
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English (en)
French (fr)
Inventor
John Erik Hershey
Pietro Patrone Bonissone
Charles Terrace Hatch
Harold Woodruff Tomlinson
Kai Frank Goebel
Naresh Sundaram Iyer
Weizhong Yan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
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General Electric Co
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Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Publication of EP1686443A1 publication Critical patent/EP1686443A1/de
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B23/00—Testing or monitoring of control systems or parts thereof
    • G05B23/02—Electric testing or monitoring
    • G05B23/0205—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults
    • G05B23/0218—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults characterised by the fault detection method dealing with either existing or incipient faults
    • G05B23/0224—Process history based detection method, e.g. whereby history implies the availability of large amounts of data
    • G05B23/0227—Qualitative history assessment, whereby the type of data acted upon, e.g. waveforms, images or patterns, is not relevant, e.g. rule based assessment; if-then decisions
    • G05B23/0229—Qualitative history assessment, whereby the type of data acted upon, e.g. waveforms, images or patterns, is not relevant, e.g. rule based assessment; if-then decisions knowledge based, e.g. expert systems; genetic algorithms

Definitions

  • the invention relates to condition monitoring, and more particularly, to methods, systems, and computer program products for implementing condition monitoring activities for machines having well-defined operating cycles.
  • Types of conditions monitored by these systems include structural defects, temperature, speed, and torque, to name a few.
  • Sensor devices may be used to monitor and measure these conditions and transducers may be utilized for converting the measurements into a graphical form that enables an evaluator to read and analyze the measurements.
  • the type of monitoring performed on a device is clearly dependent upon the type of equipment being monitored as well as the nature of its operations. Accordingly, the type of sensors utilized for monitoring conditions will also depend upon the nature of the equipment and the operations performed thereon. For example, critical operations (e.g., life-saving processes) may require some redundancy in the monitoring activities performed on an equipment device to ensure the accuracy and reliability of the equipment's informational output.
  • Sensors operating on regular running machines or those which exhibit periodic cycles of equal time characteristics (e.g., a rotating machine) generally produce signatures of similar patterns due to the cyclic nature of the operations performed on the machines. These patterns can provide some qualitative information regarding the optimal performance of the machine due to the cyclical nature of the operations. It would be desirable to provide a condition monitoring system that utilizes the signature patterns associated with regular running machines to identify and remedy issues resulting from the machine operations.
  • Exemplary embodiments of the invention relate to methods, systems, and computer program products for implementing condition monitoring activities.
  • Methods include receiving signals output by a machine being monitored, isolating and capturing a signature from the signals, digitizing and recording the signature as an event kernel, and normalizing the event kernel by performing a mean removal and normalizing the energy to unity on results of the mean removal.
  • Systems for implementing condition monitoring activities include a processor in communication with a machine being monitored.
  • the processor receives signals output by the machine via a signal conversion element associated with the machine.
  • Systems also include a display device in communication with the processor for providing signatures of the signals received from the signal conversion element.
  • Systems further include a means for identifying, isolating, and capturing a signature from the signatures presented on the display device.
  • the system also includes a means for digitizing and recording the signature as an event kernel, a means for normalizing the event kernel by performing a mean removal, and a means for normalizing the energy to unity on results of the mean removal.
  • Systems further include a storage device for storing normalized event kernels.
  • Computer program products for implementing condition monitoring activities include instructions for performing a method.
  • the method includes receiving signals output by a machine being monitored, isolating and capturing a signature from the signals, digitizing and recording the signature as an event kernel, and normalizing the event kernel by performing a mean removal and normalizing the energy to unity on results of the mean removal.
  • the condition monitoring system performs pattern recognition for event identification (i.e., time-of-occurrence estimation and event type classification) utilizing a signature associated with a regularly running machine.
  • the signature may be an acoustic/seismic signature.
  • a regularly running machine refers to one that exhibits periodic cycles of equal time characteristics.
  • the regularly running machine may be a rotating machine under a constant load.
  • the signature is digitalized and normalized utilizing a two-step process, resulting in a normalized event kernel. Computations such as autocorrelations and cross-correlations may be performed on the normalized event kernel.
  • the signature data produced from the rotating machine may be referenced to a 360-degree cycle as shown in the prior art diagram of FIG. 1.
  • the signature data depicted in FIG. 1 represents a three monitor traces 102, 104, and 106 for crosshead accelerometer data.
  • FIG. 2 includes equipment 202 in communication with a signature identification and capture station 204 and a correlator bank 206.
  • Equipment 202 refers to the machine that is being monitored. Equipment 202 may be any type of regular running machine or mechanical device as described above. For purposes of illustration, equipment 202 is a turbine engine. Equipment 202 includes a rotor 214, which further comprises a shaft (not shown). Equipment 202 also includes a signal conversion element 210 (e.g., a transducer and/or shaft encoder) that converts acoustic/seismic data output from equipment 202 into a digitized form. The shaft encoder, for example, may output digital pulses corresponding to incremental angular motion of the equipment shaft and registers the signatures produced with the shaft's angular position.
  • a signal conversion element 210 e.g., a transducer and/or shaft encoder
  • Signature identification and capture station 204 includes a display device 205 for presenting visual data (traces) received by equipment 202.
  • Signature identification and capture station 204 may comprise a processor device executing a module (e.g., software application) that enables an operator of the signature identification and capture station 204 to identify and select portions of the monitor trace on the display device 205 to be used in the implementation of the condition monitoring activities described herein.
  • a selected signature 212 from the trace is shown on the display device 205 of signature identification and capture station 204.
  • Correlator bank 206 refers to a collection of correlators or kernels, which may represent different instances of a same event, or different types of events. The correlations may be implemented utilizing a variety of techniques (e.g., convolution in the Fourier domain). Correlator bank 206 may comprise a storage device. Correlator bank 206 is in communication with a monitor 208. Monitor 208 displays the cross-correlations of the event kernels against operational data as described further herein. Monitor 208 may include exceedance alarms, logging, and statistical capabilities. While shown in FIG.
  • monitor 208 may comprise a single unit (e.g., a high-speed computer processor). Alternatively, these elements may be incorporated into the equipment 202 being monitored.
  • FIG. 3 a flow diagram describing a process for implementing the condition monitoring activities in exemplary embodiments will now be described.
  • the process begins at step 302, whereby an operator of the signature identification and capture station 204 who is monitoring a trace associated with equipment 202 identifies an event (i.e., signature) of interest 212 at step 304.
  • the operator locates events of interest in terms of angular intervals over the 360-degree machine cycle. For example, an isolated event (or signature) that occurs at approximately 60-70 degrees is shown in FIG. 4.
  • the isolated signature (i.e., signature of interest) 212 is digitized and recorded in correlator bank 206 as an event kernel via the transducer 210 and the signature identification and capture station 204.
  • High-pass filtering techniques of the signal may be employed to eliminate any low frequency components contained in the original signal. Since the relevant information related to the signature of interest 212 is expected to exist in the high frequency components in the vicinity of the event, removal of low frequency components may potentially improve detection reliability.
  • the event kernel is normalized via the signature identification and capture station 204 utilizing a two-step process as provided below.
  • S ⁇ S ⁇ i 1 n s i 2 ( energy normalized to unity )
  • a sample normalized event kernel 500 for the isolated signature is shown in FIG. 5 and may be displayed on monitor 208 at step 310.
  • Energy normalization ensures that the normalized set of samples result in a signal with energy equal to unity. This further ensures that the correlation computations performed result in true correlation coefficients, which is typically desired in assigning semantics to the acyclic correlation plots.
  • computation of the acyclic autocorrelation of the normalized event kernel 500 may be performed at step 312 in order to determine whether it will have good localization capability.
  • a sample acyclic autocorrelation of the event kernel is displayed at step 314 on monitor 208 as shown in FIG. 6. It will be appreciated that the peak to maximum sidelobe ratio of the acyclic autocorrelation of the event kernel as depicted in FIG. 6 is not insignificant. This may indicate that the data representing the normalized event kernel is not nearly independent, and localization of the event may not be as sharp as it might be with more nearly independent data.
  • the autocorrelation data may, however, indicate that the signature may be sufficient for nominal demands of angular localization.
  • the correlation data also contains information about whether or not the event is present in another trace. Hence it can also be used merely for the detection of the presence or absence of an event in a given signal trace. This is important in applications where the event signature can be expected to change under unhealthy operating conditions. In such a case, the correlation plot using the stored event kernel will not produce any strong peaks and the absence of a strong correlation can be used to infer that the event signature has changed, thereby signaling the presence of potential anomalous operation.
  • a suitable threshold can be used on the correlation plot to ascertain the presence or absence of the event by determining whether or not any portion of the correlation signal is greater than the threshold as a means to infer the presence of the event signature of interest.
  • the condition monitoring system computes the sliding cross-correlation of the normalized event kernel 500 against the top trace 102 of FIG. 1 from which the event kernel was extracted.
  • the portion of the trace within the sliding window is normalized to zero mean and energy equal to unity before performing the cross-correlation.
  • the cross-correlation is displayed on monitor 208 at step 316 and a sample cross-correlation of the event kernel (including monitor data) is shown in FIG. 7.
  • the peak value of the correlation plot is used to mark the time of event occurrence within the trace or signal being examined.
  • a threshold-specific examination of the correlation signal can be used to infer whether or not the event signature of interest is present.
  • the condition monitoring system evaluates the repeatability of the event kernel over the same equipment 202 within the same machine state. This may be accomplished by performing a sliding cross-correlation computation of the normalized event kernel 500 against, e.g., the middle trace 104 of FIG. 1. Again, the portion of the trace within the sliding window is normalized to zero mean and energy equal to unity prior to the cross-correlation.
  • the results of the cross-correlation computation of step 318 is displayed on monitor 208 and a sample representation is shown in FIG. 8. Note that a useful cross-correlation peak appears but is reduced over its performance as shown in FIG. 7.
  • the difference in cross-correlation performance is due to noise.
  • the variance of the cross-correlation may be estimated from a collected set of event kernels at step 324.
  • the described process is implemented using data sampled and retained at ultrasonic range. This is motivated by the fact that machine noise in the ultrasonic range is expected to be quite low. This is expected to improve the sensitivity of event detection using cross-correlation as described here.
  • FIG. 9 indicates a time trace 900 as well as signatures visible in a corresponding power spectral density plot 902, which shows the amount of noise present in the signal. It is clear that the surrounding machine noise that is present in the region 904, or lower frequency region, is significantly reduced in ultrasonic region 906.
  • Creating kernels using data present in region 906 is expected to improve the performance on event localization.
  • the process may involve using a band-pass filter or high-pass to retain signal information pertaining to region 906 only and then using it for the extraction of kernels.
  • FIG. 10 illustrates an active acoustic machinery diagnostic analyzer 1000.
  • the analyzer 1000 comprises a display/interface 1005, as well as a controller/processor unit 1010 that controls the actions of the analyzer.
  • the analyzer further comprises a transmitter module 1020 that generates acoustic waveforms that are applied to cabled active acoustic transducers 10301-1030M where M is at least 1.
  • the active acoustic transducers are attached to the housing of the machinery 1040 under diagnosis 1040.
  • the active acoustic transducers 1030 1 -1030 M radiate specially crafted excitation signals 1045 into the machinery 1040 under diagnosis.
  • the signals 1045 may comprise audio and ultrasonic components.
  • the signals 1045 interact with the moving parts 1060 of the machinery 1040 under diagnosis.
  • the interactions modify the reflections of the signals 1045 to produce signals 1050.
  • the signals 1050 may reveal the position and condition of various moving parts by a changing attenuation profile or the movement of a part may result in a change in Doppler.
  • the signals 1050 may be a frequency translation of the signals 1045 by an interaction with a moving rod.
  • the signals 1050 are conducted through the housing of the machinery 1040 under diagnosis and sampled by cabled passive acoustic transducers 10251-1025N where N is at least 1.
  • the sampled signals can be directly used to extract kernels and apply them for event detection in other traces.
  • the condition monitoring system performs pattern recognition for event identification (i.e., time-of-occurrence estimation and event type classification) utilizing a signature associated with a regularly running machine (e.g., one that exhibits periodic cycles of equal time characteristics).
  • the signature may be an acoustic/seismic signature.
  • the signature is digitalized and normalized utilizing a two-step process, resulting in a normalized event kernel. Computations such as autocorrelations and cross-correlations may be performed on the normalized event kernel.
  • the embodiments of the invention may be embodied in the form of computer implemented processes and apparatuses for practicing those processes.
  • Embodiments of the invention may also be embodied in the form of computer program code containing instructions embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or any other computer readable storage medium, wherein, when the computer program code is loaded into and executed by a computer, the computer becomes an apparatus for practicing the invention.
  • An embodiment of the present invention can also be embodied in the form of computer program code, for example, whether stored in a storage medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the computer program code is loaded into and executed by a computer, the computer becomes an apparatus for practicing the invention.
  • the computer program code segments configure the microprocessor to create specific logic circuits.
  • the technical effect of the executable code is to perform pattern recognition for event identification such as time-of-occurrence estimation and event type classification.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Bioinformatics & Cheminformatics (AREA)
  • Bioinformatics & Computational Biology (AREA)
  • Evolutionary Biology (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
  • Testing And Monitoring For Control Systems (AREA)
EP06250485A 2005-02-01 2006-01-30 Verfahren ,Systeme und Computerprogramme zur Durchführung von Zustandsüberwachungen Withdrawn EP1686443A1 (de)

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US8989501B2 (en) * 2012-08-17 2015-03-24 Ge Aviation Systems Llc Method of selecting an algorithm for use in processing hyperspectral data
US8891875B2 (en) * 2012-08-17 2014-11-18 Ge Aviation Systems Llc Method of evaluating the confidence of matching signatures of a hyperspectral image
US8988238B2 (en) 2012-08-21 2015-03-24 General Electric Company Change detection system using frequency analysis and method
EP3477983B1 (de) 2016-09-21 2020-06-03 Swisscom AG Datengesteuertes lieferungsplanungoptimierungsverfahren

Citations (2)

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US20040078171A1 (en) * 2001-04-10 2004-04-22 Smartsignal Corporation Diagnostic systems and methods for predictive condition monitoring

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US20040078171A1 (en) * 2001-04-10 2004-04-22 Smartsignal Corporation Diagnostic systems and methods for predictive condition monitoring

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